In a long term evolution-advanced (LTE-A) communications system, an evolved nodeB (eNB) transmits to a user equipment (UE) a downlink demodulation reference signal (DMRS). The UE performs channel estimation by utilizing the downlink DMRS, and further performs data demodulation. The eNB also transmits to the UE a channel-state information reference signal (CSI-RS), the UE performs channel estimation by utilizing the CSI-RS, and further performs channel-state information feedback. Where, a parameter in a DMRS initialization sequence and a parameter in a CSI-RS initialization sequence are configured for the UE by the eNB via a higher layer signaling.
In addition, the eNB will configure other configuration information of the CSI-RS and an uplink reference signal for the UE via a higher layer signaling. Where, other configuration information of the CSI-RS includes at least one of the parameters as follows: the number of CSI-RS ports, a reference signal pattern, a period and a subframe offset, a ratio of energy per resource element (EPRE) of a physical downlink shared channel (PDSCH) to EPRE of a CSI-RS, etc. The uplink reference signal includes at least one of the parameters as follows: an uplink demodulation reference signal, a sounding reference signal (SRS), etc.
Nevertheless, there is no solution regarding how the eNB configures the suitable reference signal for the UE.